The present invention includes a method for determining a soil classification comprising: obtaining a soil sample; conducting two or more of the following tests in the field, wherein the tests are selected from wash test, a feel test, a test tube particle graduation, or a jar test, to obtain raw data for each test; and calculating the soil classification from the raw data obtained in the field by applying a previously obtained validation dataset obtained from a training and validation soil classification calculation using known samples. The invention also includes compressed earth blocks made using the present invention.